Validating a questionnaire

For such studies, accurate methods to assess middle or long-term dietary intake are needed.However, comprehensive dietary methods are often expensive, time consuming and request a high commitment of participants [].

The relative validity of this questionnaire was studied among participants of another nationwide survey, the German National Nutrition Monitoring (NEMONIT).Cross-sectional comparisons of food consumption data from the FFQ and from two 24-hour recalls were made in a sample of 161 participants (aged 18 to 80 years) of an ongoing nationwide survey, the German National Nutrition Monitoring (NEMONIT).The data collection took place from November 2008 to April 2009.For the other food groups, the estimates of food consumption by the FFQ were not generally higher or lower than estimates from the 24-hour dietary recalls.The FFQ appears to be reasonably valid in the assessment of food consumption of German adults.The proportion of participants classified into the same or adjacent quartile of intake assessed by both methods varied between 68% for cooked vegetables and 94% for coffee.